Retinal thickness in the central retina is frequently used to detect diseases in their early stages, and to monitor the effectiveness of treatment. Generally, images and data obtained with optical coherence tomography (OCT) systems are used. A standard spectral OCT system typically splits light from a single source into two parts, each of which traverses a different path in an interferometer. One path, called the reference path, simply introduces a variable delay into the beam travelling the reference path. The other path, called the object path, travels to and scatters back from a patient's eye. The light scattered back from the patient's eye is mixed with light from the reference path to produce an interference signal. The interference signal is analyzed with a spectrometer. For a usable OCT signal to be produced the two paths must be matched in length. However this means that patient movement tends to be an issue. Complicated image processing must be performed in order to compensate for patient movement when determining the retinal thickness when using a standard OCT system.
There is a need to provide a method of measuring retinal thickness using a simpler procedure, and which preferably does not depend on lack of movement by the patient.